A motor is a device that is used to covert electrical energy to mechanical energy, and typically includes a stator and a rotor. The rotor is configured to rotate by a force that is generated electromagnetically between the stator and the rotor.
Since a spoke-type permanent magnet motor using permanent magnets to generate a magnetic field has structurally high magnetic flux concentration, the spoke-type permanent magnet motor can generate high torque and high power, and is thereby capable of reducing the size of the motor while producing the same or greater output power. Accordingly, the spoke-type permanent magnet motor may be used as a drive motor for washing machines, air conditioners, vacuum cleaners, and the like, that require such high torque and high output characteristics.
FIGS. 1 and 2A are views illustrating an example of a spoke-type permanent magnet motor according to the related art.
Referring to FIGS. 1 and 2A, a spoke-type permanent magnet motor 1 includes a stator 20, a rotor 30, and a motor shaft 40.
The rotor 30 disposed inside the stator 20, is rotated with respect to the stator 20, and is integrally provided with the motor shaft 40 in the center of the rotor 30.
The rotor 30 also includes a plurality of permanent magnets 31 arranged in a radial shape relative to the motor shaft 40, a core 32 that supports the plurality of permanent magnets 31 and forms a passage of magnetic flux, and an injection ring 33 to cover the permanent magnets 31 and the core 32.
However, the spoke-type permanent magnet motor 1 may have a problem in that the permanent magnets 31 become separated from the core 32 or that parts of the injection ring 33 covering the permanent magnets 31 become separated from the core 31, become deformed, or are broken by a centrifugal force generated while the rotor 30 rotates at a high speed.
In order to prevent the problem, the motor 1 of the related art includes a structure that is capable of preventing the permanent magnets 31 and the injection ring 33 from becoming separated from the core 32 as illustrated in FIG. 2B.
FIG. 2B is an enlarged partial view illustrating a portion of a rotor of a spoke-type permanent magnet motor according to the related art.
Referring to FIG. 2B, a fixing protrusion 35 for supporting the permanent magnet 31 and a fixing groove 36 for holding the injection ring 33 are provided at an outer end of a magnet fixing hole 34 of the core 32. The fixing protrusion 35 can prevent the permanent magnets 31 from being extracted from the magnet fixing hole 34 by the centrifugal force generated when the rotor 30 rotates. Also, because a portion of the injection ring 33 is inserted into the fixing groove 36, the injection ring 33 may be prevented from becoming separated from the core 32 by the centrifugal force when the rotor 30 rotates.
However, since the structure of the motor 1 of the related art for preventing separation of the permanent magnets 31 and injection ring 33 is formed so that the fixing protrusion 35 for fixing the permanent magnet 31 and the fixing groove 36 for holding the injecting ring 33 are overlappingly formed in the radial direction of the rotor 30 at the outer end of the magnet fixing hole 34 receiving the permanent magnet 31, the size of the separation preventing structure of the permanent magnet 31 and the injection ring 33 is large. In particular, a distance g1 between the outer end of the permanent magnet 31 and the outer circumferential surface of the rotor 30 is large. Accordingly, when the radius R of the rotor 30 is maintained at a standard size, there is a resulting problem where the size of the permanent magnet 31 must be reduced. When the size of the permanent magnet 31 is reduced, there is a resulting problem where the maximum output torque of the motor 1 is also reduced.
The above information is presented as background information only, to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.